rockchip: dts: tinker: Add tinker-s board support

Support tinker-s board. The board is equivalent of tinker board
except of emmc.

TODO:
- support of usb current burst when the board is powered from pc

Signed-off-by: Michael Trimarchi <michael@amarulasolutions.com>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>
diff --git a/board/rockchip/tinker_rk3288/MAINTAINERS b/board/rockchip/tinker_rk3288/MAINTAINERS
index cddceaf..ed5de68 100644
--- a/board/rockchip/tinker_rk3288/MAINTAINERS
+++ b/board/rockchip/tinker_rk3288/MAINTAINERS
@@ -4,3 +4,10 @@
 F:	board/rockchip/tinker_rk3288
 F:	include/configs/tinker_rk3288.h
 F:	configs/tinker-rk3288_defconfig
+
+TINKER-S-RK3288
+M:	Michael Trimarchi <michael@amarulasolutions.com>
+S:	Maintained
+F:	board/rockchip/tinker_rk3288
+F:	include/configs/tinker_rk3288.h
+F:	configs/tinker-s-rk3288_defconfig